scholarly journals The Influence of Crushed Limestone Aggregate on the Properties of Concrete^|^mdash;Fine Particle Contents, Drying Shrinkage, ASR, Sulfate Deterioration, Compressive Strength^|^mdash;

2012 ◽  
Vol 50 (10) ◽  
pp. 904-911
Author(s):  
K. Tada ◽  
N. Takao ◽  
K. Yamada ◽  
H. Kawano
2012 ◽  
Vol 2 (1) ◽  
pp. 21-28
Author(s):  
R. G. Solís ◽  
E. Moreno ◽  
E. Arjona

RESUMENLa resistencia del concreto depende de la calidad de la pasta de cemento y de las características de los agregados pétreos. La primera es controlada por la relación agua - cemento, mientras que las propiedades de los agregados generalmente no pueden ser manipuladas ya que se suele utilizar aquellos que están disponibles cerca de la construcción. En muchas regiones rocas con propiedades no deseables son utilizadas como agregado. Por lo tanto, el objetivo de este trabajo fue responder a la pregunta sobre cuál sería la máxima resistencia de diseño que se podría utilizar para concretos fabricados con un tipo específico de agregados obtenidos a partir de la trituración de roca caliza de alta absorción. Se probaron concretos con seis relaciones agua - cemento y dos tamaños de agregado grueso. Se concluyó que con los agregados estudiados es posible fabricar concretos de hasta 500 k/cm2 de f’c.Palabras clave: Absorción; agregados calizos; concreto; relación agua/cemento; resistencia.ABSTRACTConcrete strength depends on the cement paste quality and on the characteristics of the aggregates. The former is controlled by the water to cement ratio, while the properties of the aggregate, in general, cannot be manipulated as it is customary to employ the ones available near the construction site. In many regions rocks with no desirable properties are employed as aggregates. Therefore, the aim of this study was to answer the question about what would that be the maximum compressive strength attainable in concrete made with a specific type of aggregate obtained from crushed limestone of high absorption. Concrete mixtures involved six water to cement ratios and two sizes of coarse aggregate. It was concluded that with this type of aggregate it is possible to made concrete with compressive strength up to 500 k/cm2 of f’c.Key words: Absorption; compressive strength; concrete; limestone aggregate; water/cement ratio.


2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Luigi Coppola ◽  
Denny Coffetti ◽  
Sergio Lorenzi

The paper focuses on the evaluation of the rheological and mechanical performances of cement-based renders manufactured with phase-change materials (PCM) in form of microencapsulated paraffin for innovative and ecofriendly residential buildings. Specifically, cement-based renders were manufactured by incorporating different amount of paraffin microcapsules—ranging from 5% to 20% by weight with respect to binder. Specific mass, entrained or entrapped air, and setting time were evaluated on fresh mortars. Compressive strength was measured over time to evaluate the effect of the PCM addition on the hydration kinetics of cement. Drying shrinkage was also evaluated. Experimental results confirmed that the compressive strength decreases as the amount of PCM increases. Furthermore, the higher the PCM content, the higher the drying shrinkage. The results confirm the possibility of manufacturing cement-based renders containing up to 20% by weight of PCM microcapsules with respect to binder.


2021 ◽  
Vol 11 (3) ◽  
pp. 1037
Author(s):  
Se-Jin Choi ◽  
Ji-Hwan Kim ◽  
Sung-Ho Bae ◽  
Tae-Gue Oh

In recent years, efforts to reduce greenhouse gas emissions have continued worldwide. In the construction industry, a large amount of CO2 is generated during the production of Portland cement, and various studies are being conducted to reduce the amount of cement and enable the use of cement substitutes. Ferronickel slag is a by-product generated by melting materials such as nickel ore and bituminous coal, which are used as raw materials to produce ferronickel at high temperatures. In this study, we investigated the fluidity, microhydration heat, compressive strength, drying shrinkage, and carbonation characteristics of a ternary cement mortar including ferronickel-slag powder and fly ash. According to the test results, the microhydration heat of the FA20FN00 sample was slightly higher than that of the FA00FN20 sample. The 28-day compressive strength of the FA20FN00 mix was approximately 39.6 MPa, which was higher than that of the other samples, whereas the compressive strength of the FA05FN15 mix including 15% of ferronickel-slag powder was approximately 11.6% lower than that of the FA20FN00 mix. The drying shrinkage of the FA20FN00 sample without ferronickel-slag powder was the highest after 56 days, whereas the FA00FN20 sample without fly ash showed the lowest shrinkage compared to the other mixes.


2018 ◽  
Vol 203 ◽  
pp. 06022
Author(s):  
Salmia Beddu ◽  
Daud Mohamad ◽  
Fadzli Mohamed Nazri ◽  
Siti Nabihah Sadon ◽  
Mohamed Galal Elshawesh

This study investigates the self-curing concrete using baby polymer diapers as substitute method of curing process in order to improve mechanical and physical properties of concrete. Three different proportion of baby polymer diapers which are 1%, 3% and 5% were mix with concrete. Slump, compressive strength and drying shrinkage test were performed in order to study the workability, strength and durability of the concrete. All concrete were tested for 1, 3, 7, 14, and 28 days for drying shrinkage test. Meanwhile, all concrete were test at 3, 7 and 28 days for compressive strength test. Compressive strength of concrete containing 5% baby polymer diapers show the highest strength at 28 days compared to others percentage. Thus, it indicates that application of baby polymer diaper as self-cure agent can improve the concrete performances.


Author(s):  
Nguyen Van Chinh

Drying shrinkage is the main cause of early age cracking of concrete and mortar. A wide range of research has been conducted to reduce the drying shrinkage, including using fibres or chemical admixtures. This paper investigated the effect of shrinkage reducing admixture on the flexural strength, compressive strength, drying shrinkage, water absorption and porosity of mortar. The mix compositions were ordinary Portland cement (OPC) : sand : liquid = 1: 1: 0.38 in which liquid consisted of water and shrinkage reducing admixture (SRA). SRA was used at the proportions of 2%, 4%, and 7% by weight of cement. The test results show that SRA reduces the flexural and compressive strengths of mortar. The reduction in flexural strength and compressive strength at 28 days is 14% and 25%, respectively at 7% SRA dosage. In addition, SRA significantly reduces the drying shrinkage and water absorption of mortar. At 7% SRA dosage, the drying shrinkage at 53 days is reduced by 60% while the water absorption rate at 24 hours is reduced by 54%. However, SRA has a minor effect on the pore size distribution, effective porosity, and cumulative intrusion volume of mortar.


2010 ◽  
Vol 152-153 ◽  
pp. 1176-1179 ◽  
Author(s):  
Feng Lan Li ◽  
Qian Zhu

To improve the application of the new proto-machine-made sand in structural engineering, tests are carried out to study the drying shrinkage of concrete affected by stone powder in proto- machine-made sand. The target cubic compressive strength of concrete is 55 MPa, the main factor varied in mix proportion of concrete is the contents of stone powder by mass of proto-machine-made sand from 3 % to 16 %. The drying shrinkage strains of concrete are measured by the standard method at the ages of 1 d, 3 d, 7 d, 14 d, 28 d, 60 d, 90 d, 120 d, 150 d and 180 d. Based on test results, the drying shrinkage of concrete affected by the contents of stone powder in proto-machine-made sand is analyzed and compared with that of similar test of concrete with traditional machine-made sand, which shows that there is the optimum content of stone powder resulting in the lower drying shrinkage of concrete. The formula for predicting drying shrinkage strain of concrete is proposed.


Author(s):  
Haruka Murakami ◽  
Hiromi Fujiwara ◽  
Masanori Maruoka ◽  
Takahumi Watanabe ◽  
Koji Satori

In recent years, as structures become higher, larger, and more durable concrete whose compressive strength of the concrete is 150 N/mm 2 or more have been put to practical use. It is for this reason that it is necessary to develop strengthening materials with equal or better performance. Furthermore, the development of high-performance concrete repair materials is carried out because demand to seismic strengthening and repair increases. In this study, considering these circumstances, it was conducted an experimental study with the aim of developing a repair material using room temperature curing UFC (R-UFC). A binder composition preparation of the R-UFC has excellent fluidity under pressure. It was achieved that high-grade thixotropy, high compressive strength, and high bending strength. It can also be sprayed continuously because of its high thixtoropy. It was confirmed that the sprayed thickness was reached to 20mm by one work. Durability of this R-UFC was investigated and it was confirmed the high sulfate resistance, small drying shrinkage and low salt permeability.


2003 ◽  
Vol 17 (2) ◽  
pp. 105-112 ◽  
Author(s):  
M Maslehuddin ◽  
Alfarabi M Sharif ◽  
M Shameem ◽  
M Ibrahim ◽  
M.S Barry

2014 ◽  
Vol 878 ◽  
pp. 194-198 ◽  
Author(s):  
Peng Guan Li ◽  
Feng Qing Zhao

The load-bearing brick is made from steel slag and silicon tailings by pressing and autoclaving process. Because of the volume stability, steel slag was ground to above 320 m2/kg and wet cured in 50-60°C at 12-24 hours in the present of additives, before pressure forming and autoclaving process. Tailings account for 63% of the total mass of the brick, while steel slag 30 %. The compressive strength of the brick was up to 13.1MPa, bending strength 3.2MPa, and with low drying shrinkage and good freeze-thaw resistance. The application conditions were discussed.


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